Domain morphology and temperature- dependent piezoelectricity in terms of piezoelectric coefficient d(33) and normalized strain d(33)* of (K, Na, Li)(Nb, Ta, Sb) O-3 lead-free piezoceramics at the polymorphic phase boundary were investigated. Transmission electron microscopy (TEM) and piezoresponse force microscopy (PFM) studies revealed a characteristic domain morphology comprising strip-like domains and featureless domains. Moreover, a facile method based on the field-dependent piezoelectric coefficient d33(E) measurement was verified to characterize in situ temperature dependence of piezoelectric coefficient d33, as an alternative for the conventional ex situ route. It was demonstrated that the normalized strain d33* exhibits superior thermal resistance to piezoelectric coefficient d33, though both parameters are susceptible to temperature variation.